Expert: Dr. Henry Boyter, Jr. - 3/18/2004

Question
I am part of a group of students who are interested in finding out just what is in a nearby river that has been considered for drinking water use.  We've taken a couple of samples from different places, including near a very big paper manufactorer and an industrial complex, and our Chemistry teacher has given us lab space.  However, we have no idea how to go about testing for the presence of specific metals, or what we should be looking for.  Our idea is to dry out different water samples and filter, then use solubility rules to see if other precipitates form when we mix reactions.  We're thinking about looking for Mercury, Lead, and Arsenic.  Are there specific detectors for these metals and others?  We're stuck!

Answer
Those three metals can not be done without very specific expensive equipment.  For example, a color or solubility test for lead will work at about 0.5 mg/L, but to examine for drinking water, you need to get down to 0.015 mg/L.  Same for mercury and arsenic.  Those industries will not be discharging those metals above the drinking water levels.

You might look at the Secondary Drinking Water Standards
http://www.epa.gov/safewater/mcl.html#sec
http://www.epa.gov/safewater/consumer/2ndstandards.html

Of these, odor, chloride, color, Fe, Mn, Zn, and dissolved solids can be done in a regular lab seeting.  You will need to search the www.epa.gov webpages for the methods or go to the library (for the metals).  Start with http://www.epa.gov/safewater/methods/methods.html  A good google search is also imperative.